Material handling apparatus



July 16, 1940. D. w. KENT El AL 2,207,987

MATERIAL HANDLING APPARATUS Original Filed Aug. 6, 1935 3 Sheets-Sheet l I H H i I 8 a =1 1 j t d n 8 II I I I H N gr!) 3 Q m N INVENTORS DONALD wnumaw mewr FBEED VAN 000/? July 16, 1940. D. w. KENT ET AL MATERIAL HANDLING APPARATUS Original Filed Aug. 6, 1935 3 Sheets-Sheet 2 INVENTORS FEED 0 m m D July 16, 1940. D. w. KENT ET AL MATERIAL HANDLING APPARATUS Original Filed Aug. 6, 1935 3 Sheets-Sheet 5 I INVENTORS .DONALD WETHE/MLD KENT FRED VAN DOON/NCK Patented July 16, 1940 ArENr 2,207,987 MATERIAL HANDLING APPARATUS Donald Wetherald Kent, Barron Hill, and Fred Van Doorninck, Easton, Pa., assignors to C. K. Williams & 00., Easton, Pa., a corporation of Pennsylvania Application August 6, 1935, Serial No; 34,876

Renewed December l, 1938 6 Claims.

This invention relates to improvements in heat transferdevices and more particularly to an improved rotary muffle type material handling apparatus which may be adapted either for heating or cooling the materials processed.

The rotarymuflle has heretofore been used for the uniform heating of products as required in well known. commercial processes because of the evenness of heat transfer due to the overrun.- ning, material which constantly exposed new surfaces. As the materials treated only form a shallow layer at the bottom of the drum, however, increase in through-put, can. only be had by larger drums or higher temperaturesor a greater speed which would normally cause a greater rate of overrunning and therefore greater frequency of formation of new layers for heat treatment. Larger apparatus is of course most expensive, for mufiles are not variable in sizewithout also reconstructing the furnace, and temperatures are limited by the materials undergoing treatment.

Increases of the speed of rotation of the drum or the thickness of layer of the treated material is also limited-by practical conditions, especially at high temperatures, and transfer of heat can not be improved by this means beyond a certain point. In addition, the low rate of heat transfer of many of the materials to be treated is such that layers in excess of two inches have often been found impractical andunsatisfactory. The industry has therefore found that it was necessary to use more mufiles, or to use larger ones both in diameter and length for increased production.v

It is one of the objects of this invention to increase the capacity of a rotary muffle without changing its size by providing an intermediate tube or muflle and, providing inwardly projecting flights to facilitate transfer of the materials-handledfrom one muffle surface to the other.

.A further object of this invention is to provide an improved heat treating apparatus consisting. of a drum with internally open pockets and having interior transfer means to transfer materials from one upper point on the drum to another upper point on the drum to materially increase the surfaces in active heat transfer oporation, and by virtue of the greater volume of material, a greater control of the heat transfer can be obtained. Another object of this invention is to provide a new methodof transferring heat to or from materials to be handled by alternately transferring the materials between generallyconcentric drum surfaces by overrunning of the'particles' on the respective surfaces.

Another andmore specific object of this inventionv is to provide a calcining furnace for heating materials whichhas an inner core 'cooperatively arranged within the outer muflle, both having a series of transverse flights to intercept the material flow during rotation of the muffle, and having meansto progressively move the material through the muffle. I

Another specific object of this invention is to provide a cooling apparatus for continuous surface cooling of materials and having a plurality of rotating, substantially cylindrical surfaces independently cooled.

Another object of this invention is to provide a plurality of substantially drum shapedrotary also around the diameter in a generally helical I path for increasing the effective area contacted by the overrunning material so that the throughput may be materially increased. over that of a single unbaffled drum, the speeds, materials and temperatures being the same.

Further objects and advantages of the invention will appear from the followingdescription thereof taken inconnection with the attached drawings, which illustrate preferred forms of embodiment of our invention and in which:

7 Figure 1 is a vertical longitudinal section of a calcining furnace with part in inside elevation showing the improved muffle construction; Figure 2 is a vertical section transverse to Figure 1 and showing the details of the flights;

Figure .3 is a vertical longitudinal section of a,

modified form of heat transfer muffle adapted ,for cooling materials; I

' Figure 4 is a vertical section, transverse to Figure 3, showing the internal construction, and

Figure 5is a detail of a modification of hollow flight.

Figure 6 is a crosssectional detail of a modi ficati'on of the heating arrangement.

The invention is preferably applied to a ma' Whether intended for, a uniform heating of the, materialsor for a cooling of them, or for any" Variation of the heat transferas may belfcund' desirable. A preferred form of embodiment of It is equally the invention as applied to a calcining furnace is shown in Figures 1 and 2 and in this embodiment the material to be handled and treated may enter through a suitable hopper II mounted on the fixed head 22 which is provided with sea-ling glands 24. The materials then pass through a valve or gate I2, and suitable openings I3 into the rotary muflie generally indicated at I4, which preferably comprises an outer drum I5 and an inner drum I6.

The mufile I4 is desirably supported for rota-, tion on suitable bearings I! and is rotated as by a motor I8 through a chain I9 or other well known means. The supports are such that the muffle can be rotated with a portion exposed to a heat transfer medium, in this case the combustion gases, from the furnace 20 which "forms a heating chamber 2|, surrounding the muffle I 4. The manner of heating may be varied to suit conditions but combustion gases are generally circulated for adequate heating, the source being by any well known means such as by fuel burners 20a, Rotation causes a progressive movement to be imparted to the materials, as hereinafter described, so that a continuous discharge of the heated materials takes place through the discharge head 23 which is likewise sealed by glands or other forms of sealing pack ing 24. As it is desirable that the atmosphere surrounding the materials to be handled be controlled, either for recovery or in order'to maintain a desired atmosphere in the muffie, discharge is conveniently through a gas tight sealing apparatus such as a star wheel 25, and the discharge head 23 may have any suitable gas connections found desirable.

The muffle shown in transverse cross section in Figure 2 is provided with flights 21 projecting from the outer drum in accordance with our invention, such flights or vanes preventing an accumulation of material only on the bottom of the drum as is customary in the simple drum structure. A second series of flights 28 project outward from the inner drum, and .the flights preferably have angle lips 21a and 28a respectively. These flights are so positioned that material fed into the mufiie will be engaged by the flightswhich will tend to raise the material, still on contact with the drum, until such an elevation is reached that the material falls in overrunning and it will then contact the inner drum. This will appear from Figure 2 in which the material suspended on the flights at the various points in the revolution of the drums is generally shown.

The flights 2'! on the outer drum in. moving from'the bottomto the quarter position carry' the materials to be treated with them with certain portions overrunning and forming a new layer; Due to the flights, the material is carried high on the outer drum until some point is reached between the quarter position to the half revolution position,' at which the overrunning materials tend to drop onto the flights on the inside drum, reaching a maximum at the top at which point the material has been completely transferred tothe inner drum.

Movement of the drums from the half revolution to the three-quarter position starts a transfer to the outer drum. Some of the material tirely transferred to the outer drums. The material'thus contacts with a series of baflies and outer drum, it will thus be seen that for the same outer drum diameter and length, there is according to our invention, a materially greater area of available surface for material contact as compared with the available area of a single drum, considering the same thickness of layer. The new flights also have a certain area, part of which is in contact with some materials at all times. This increase of effective area is of course variable by virtue of the relative lengths of the flights and their number, but under normal operating conditions, we find that the rate of flow through the improved muffle is of the orderof nine times that previously possible.

Heating of the inside of the drum may be accomplished by any desired means such as conduction through the metal surfaces direct from the heat of the combustion chamber 2I or from internal pipes conducting suitable combustible gases. In Fig. 6 there is illustrated a conventional arrangement for heating the interior of the drum 20 comprising a pipe I2I carryin burners I 22 with provision for carrying off waste gas, as by a pipe I23 having intake apertures I24. The .drum I20 is similar to the drum I5 of Figs. 1 and 2, and the pipes I2I and I23 pass through the end wall. Adequate heating of both. the inner and outer drums is readily accomplished and thermocouples placed at 3| and at the other places facilitate accurate control.

The materials to be treated which are usually pulverized or granular materials are moved from end to end of the drum in any desired manner as, for example, by pitch of. the muffle, why the spiral 32 as shown, or, by inclining the flights 2'! and 28. In the present form of embodi the spiral 32 extends from end to end' of the mufile chamber Ma and the flights 21 and 28 are mounted between the respective threads of the spiral. This is a positive feed construction and forms a pocket relation on both the outer and inner drums of the muffle. The inner drum I6 need not be either a closed member or a true cylinder. One of its functions of transferring material falling from one point on the outer drum to anotherpoint thereon each drum or other material advancing means may be used. The, pocket relation of the outer drum has the maximumamount of exposed space for contact with the materials handled and will carry the materials to be treated over a substant al range. For maximum efliciency both drums are provided with the flights which extend approximately half way into the muffle chamber and they may be staggered along the periphery of the respective drums.

be varied however as found desirable.

Another form of embodiment of our invention is shown in the modified apparatus illustrated in Figures 3 and 4, which is more particularly adapted for cooling purposes.

The relationship may In this construction, the muflle 40 is also of the double drum type having an outer drum and an inner drum 42. The outer drum may preferably be of double wall type having a cooling medium chamber 43 between the inner shell forming the outer drum M and the outer shell lla. Also, in a manner similar to the first form of embodiment, the muffle chamber between the two drums is preferably closed at the end and the material to be handled is confined within the muffle chamber during the cooling.

This type of muffle includes any desired type of feeding hopper #15 from which the materials to be handled pass through a suitable valve or gate 46 and through openings 41 in the outer drum M of the muffle. The hopper and fixed head 43 are provided with suitable glands or seallng devices 49 to seal'the fixed head during rotation of the muffle. The discharge head is similarly sealed with glands or sealing devices 49 and discharge may be under any form of control found desirable, such as star wheel 5|. Rotation of the mufile is conveniently by means of a drive such as shown at 52.

The respective heads 48 and 50 are adapted to receive the rotatable ends 40a and 41112, of the mufile which desirably project through the same and have conduits 5 and 55 respectively, for the cooling medium. Manifolds 56 and 51' co operate with these ends of the muflle and act as distributors for the cooling medium. Other conduits 58 and 59 may also extend into and out of the core of the mufile to cool the interior of the mufile, conduit 58 having extending spray arms 60 for cooling, and conduit 59 having a suction.

end Bl to remove the cooling medium at the greatest distance from the inlet.

In operation of this ,form of apparatus, the material which is to be cooled passes into the muflie chamber 40a. and is moved by rotation of the mufile toward the dischargeend of the apparatus. This is accomplished bya spiral 62 although other means could be provided as heretofore mentioned. During the movement of the materials to be handled, the flights 63 and 64 projecting from the drum engage the material and as before mentioned, it is transferred from one drum to the other, both of which are independently heated or cooled as desired. In this form, the cooling chamber for the outer drum is represented at 43 as shown in Figure 4, and the inner cooling chamber is represented at 40. The internal cooling pipes may spray or expand either a gas such as a refrigerant or a cold liquid which can be removed as it collects at the bottom of the respective drums and in the liquid discharge heads 51.

A modified form of flight is shown in Figure 5 in which the drum Ill has a hollow projecting flight member II which is cooled or heated by gases entering the aperture 12 at the base. This will facilitate heat transfer under certain conditions.

The apparatus by which new surfaces of material become exposed to new surfaces of a rotating drum at a greater frequency without increase While we have shown preferred forms of embodiment of our invention, we are also aware that many modifications can be made thereto,

and we therefore desire a broad interpretation of our inventionwithin the scope and spirit of the description herein and of the claims appended hereinafter.

We claim:

'1. A calcining furnace of the class described including a muffle, said muffle having a plurality of concentric drums forming a muffle chamber therebetween and having means to raise material within the muffle chamber alternately and to spread said material over parts of both drums alternately during rotation, said raising means including a plurality of flights projecting into said muffle from both drums and engaging the material to be treated, each flight being secured to one drum and spaced from the other drum and means to rotate the muffle and means to heat said drums from without the muflie chamber.

2. A calcining furnace of the class described including a muil'ie having an inner drum and an outer drum forming a muffle chamber therebetween, means to rotate the muffle, means to apply heat to the inner surface of the inner drum and the outer surface of the outer drum, means to introduce material to be calcined into the muffle chamber and to remove material therefrom ineluding means to prevent contact of the contents of the mufiie chamber with exterior gas or air, said muffle chamber having means to raise material therein during rotation of the mufile and to spread said material over parts of both drums during rotation comprising flights alternately secured to the inner and outer drums and projecting into said muffle chamber.

3. A heat exchange apparatus of the class described for treating granular and pulverulent material comprising a muffle having concentric drums with a muffle chamber therebetween, spiral vane means for advancing material from one end of said muffle to the other, means for distributing the material over the surfaces of both drums comprising flights secured to the outer drum and projecting radially inward but spaced from the inner drum and flights secured to the inner drum and extending radially outward but spaced from the outer drum and means for heating the material while excluding the heating medium from contact with the material.

4. A calcining furnace as defined in claim 2, wherein the outer drum is formed with a plurality of feed openings and having means for feeding material by gravity through said openings into the muffle chamber.

5. In an apparatusof the character described having outer and inner drums forming a muffle chamber therebetween, a plurality of pickup vanes projecting from the outer surface of the inner drum and the inner surface of the outer drum adapted to raise a material to be treated, said vanes being of T-shape to provide pockets for material handled and being so spaced as to alternately transfer said material between said drums during a single revolution andmeans to revolve the drums.

6. A calcining furnace as described in claim 1, wherein the flights are of T-shape to provide material holding pockets on both sides of each flight.

DONALD w. KENT.

FRED VAN DOORNINCK. 

